Recently, due to the exhaustion of fossil energy and environmental pollution, the interest in electric products, which may operate with electric energy instead of fossil energy, is growing more and more.
Accordingly, with the increasing development and consumption of mobile devices, electric vehicles, hybrid vehicles, power storage devices, uninterrupted power supplies, or the like, the consumption of secondary batteries as energy sources are rapidly increasing as well as its various forms thereof. Therefore, secondary batteries are being studied very actively to cope with such diverse demands.
In particular, a device using a high-power large-capacity battery, such as an electric vehicle or a hybrid vehicle, needs to maintain good isolation between the device and the battery. If not, bad isolation of the battery brings a leakage current, which causes various problems. For reference, a leakage current causes unexpected discharge of the battery or malfunctions of electronic components provided at the device. In addition, in case of a device using a high voltage battery, such as an electric vehicle, a leakage current may give a fatal electric shock to a person. Therefore, in order to solve problems caused by such a leakage current, various kinds of isolation resistance measuring devices for determining an isolation state of a secondary battery are being developed and used.
Meanwhile, if an isolation resistance calculated by an isolation resistance measuring device is not accurate, the advantageous effects of the device deteriorates and is not able to solve various problems caused by a leakage current. In particular, if a problem arises at a voltage detection element included in a device for measuring isolation resistance or a control element for calculating isolation resistance, it is impossible to measure an accurate isolation resistance value, and the measured isolation resistance value is untrustworthy. Therefore, there is a demand for an apparatus and method which may diagnose whether a fault arises at the isolation resistance measuring device.